The Columella Aiiris in Amphibia. 567 



to the fenestra ovalis: it looks outwards and backwards; the thick, 

 oval closely fitting stapes (operculum) remains cartilaginous and is 

 only attached to the supensorium by ligaments." In a foot-note he 

 adds: "Mr. A. Doran has shown me a stapes, said to belong to this 

 species, which is ossified and has a stalk. I find nothing of the kind 

 in the specimen dissected by mej and I think it probable that that 

 specimen (in the Hunterian museum) belonged to another kind." 

 It is quite likely that Mr. Doran was correct and that the stilus had 

 by some accident been torn from Parker's specimen. The relation 

 of the stilus to the artery, vein and facial nerve is typical. 



The operculum occupies the typical position below and behind 

 the columella filling the definitive fenestra vestibuli. It is a 

 relatively large hemispherical mass of cartilage free all round, at- 

 tached to the lips of the fenestra by membrane only. The cephalic 

 fourth is overlapped by the caudal margin of the columella precisely 

 as in Ambystoma. This is made clearer by an examination of 

 Fig. 41 (PI. V), a photograph showing the operculum internal to 

 an overhanging lip of cartilage, the columella, which conceals the 

 entire cephalic and a portion of the dorsal margin of the operculum. 

 In tracing it forward, it gradually diminishes and finally disappears 

 in the middle region of the perilymphatic prominence. The photo- 

 graph reproduced in Pig. 42 (PI. V) is of a section in this region, 

 and shows a small lip of cartilage, a backward continuation of the 

 columella, projecting from the ear capsule upon the dorsal margin 

 of the fenestra. Fig. 65 (PI. X) is a schematic representation of 

 the position and relations of the columella and operculum as viewed 

 from the side. 



The perilymphatic prominence is pronounced. To the caudal 

 surface of the operculum is attached the strong M. opercularis which 

 extends caudad to the suprascapula. 



Wiedersheim ('77, p. 504), in commenting upon the columella 

 in Salamandra, says: "It is cartilaginous throughout life and rests 

 suspended by the connective tissue in the foramen ovale which is 

 bordered by two thick, crest-like lips. These lips now pass forward 

 and outward in a thin cartilaginous process and this joins the 

 quadrate cartilage, — a remarkable variation of the relations described 



